THE PROBLEM OF OIL POLLUTION O F THE SEA
227
feasible to provide a mechanical collector of some sort. If the area is
small, a floating separator is often used, pumping its harvest ashore ;
it may merely remove the surface Sayer, create a cyclone-separation
vortex or concentrate the oil with rotating cylinders (the " Earle
system "). I n larger docks and waterways a variety of special vessels
has been used. They include barges with weir intakes and gravity
separation such as " Norfolk Skimmer " (U.S. Navy Yard-see
Schneider and Beduhn, 1967) or " Waferwisser " (Shell, Holland)
whose outriggers hinge on each side to form a " vee-boom " collector,
and those which use rotating cylinders or an endless belt to exploit
the greater surface-adhesion of oil, such as " Port Service " (Baltimore
-see the Batelle-Northwest Report, 1967) or " Sea Sweeper '' (BP/
Harmstorf-see Lane, 1967). Skimmers using weirs or ramps t o draw
off the surface layer cannot operate in waves and are not very manceuvrable ; those with adhesion collectors have overcome these difficulties
but the oil-water mixture which they pick up will not separate properly
in rough-water conditions. I n more open harbours it will therefore be
impossible t o contain spilt oil or t o recover it from the water by mechanical means. For economy of effort and materials, as well as the
conservation of amenity and shore life, the oil should nevertheless be
dealt with while still afloat whenever this is possible.
I n estuaries there is often a problem of responsibility ; it may take
months to identify and prosecute the culprit, while the body which is
in the best position to deal promptly with the spill may lack the
authority to allocate funds for treatment. For example, during the
" Tank Duchess " incident in the Tay Estuary (February-March 1968,
when about 90 tons of heavy crude oil leaked from a damaged tanker)
it was found that Dundee Corporation could not finance the cleansing
of waters beyond their beaches. The Harbour Trust was responsible
only if the oil were a hazard t o navigation, which it was said not t o be,
while the River Board had no jurisdiction over tidal waters and in any
case was empowered to prosecute, but not to clean up. The result of
this administrative stalemate was that after 3-4 days all the oil was
stranded over many miles of shore, some of which proved extremely
difficult and expensive to clean (Dundee Corporation Report, 1968 ;
Greenwood and Keddie, 1968). I n contrast, oil pollution incidents in
Milford Haven are investigated, treated and prosecuted by one authority, the Harbour Conservancy Board. Because of the great tidal volume
and strong currents (see Nelson-Smith, 1965) solvent-emulsifiers are
routinely used, but '' Seaspray "-a
specially equipped launchapplies them t o the slick as soon as a spill is reported. Only after the
worst incidents or in the mostt extreme conditions does oil reach the
227
feasible to provide a mechanical collector of some sort. If the area is
small, a floating separator is often used, pumping its harvest ashore ;
it may merely remove the surface Sayer, create a cyclone-separation
vortex or concentrate the oil with rotating cylinders (the " Earle
system "). I n larger docks and waterways a variety of special vessels
has been used. They include barges with weir intakes and gravity
separation such as " Norfolk Skimmer " (U.S. Navy Yard-see
Schneider and Beduhn, 1967) or " Waferwisser " (Shell, Holland)
whose outriggers hinge on each side to form a " vee-boom " collector,
and those which use rotating cylinders or an endless belt to exploit
the greater surface-adhesion of oil, such as " Port Service " (Baltimore
-see the Batelle-Northwest Report, 1967) or " Sea Sweeper '' (BP/
Harmstorf-see Lane, 1967). Skimmers using weirs or ramps t o draw
off the surface layer cannot operate in waves and are not very manceuvrable ; those with adhesion collectors have overcome these difficulties
but the oil-water mixture which they pick up will not separate properly
in rough-water conditions. I n more open harbours it will therefore be
impossible t o contain spilt oil or t o recover it from the water by mechanical means. For economy of effort and materials, as well as the
conservation of amenity and shore life, the oil should nevertheless be
dealt with while still afloat whenever this is possible.
I n estuaries there is often a problem of responsibility ; it may take
months to identify and prosecute the culprit, while the body which is
in the best position to deal promptly with the spill may lack the
authority to allocate funds for treatment. For example, during the
" Tank Duchess " incident in the Tay Estuary (February-March 1968,
when about 90 tons of heavy crude oil leaked from a damaged tanker)
it was found that Dundee Corporation could not finance the cleansing
of waters beyond their beaches. The Harbour Trust was responsible
only if the oil were a hazard t o navigation, which it was said not t o be,
while the River Board had no jurisdiction over tidal waters and in any
case was empowered to prosecute, but not to clean up. The result of
this administrative stalemate was that after 3-4 days all the oil was
stranded over many miles of shore, some of which proved extremely
difficult and expensive to clean (Dundee Corporation Report, 1968 ;
Greenwood and Keddie, 1968). I n contrast, oil pollution incidents in
Milford Haven are investigated, treated and prosecuted by one authority, the Harbour Conservancy Board. Because of the great tidal volume
and strong currents (see Nelson-Smith, 1965) solvent-emulsifiers are
routinely used, but '' Seaspray "-a
specially equipped launchapplies them t o the slick as soon as a spill is reported. Only after the
worst incidents or in the mostt extreme conditions does oil reach the